M 46 Open Cluster M46 (NGC 2437), type 'f', in Puppis
RA 07 : 41.8 (h:m); DEC -14 : 49 (deg:m); Distance 5400 light years;
Visual Brightness 6.0 (mag); Apparent Dimension 27.0 (arc min)
The cluster is very rich, with 150 stars of mag 10-13 and probably a total population of over 500. The brightest of these stars are of spectral type A0, and each about 100 times more luminous than the Sun.
As a special and famous feature which is also visible in my image, a planetary nebula (NGC 2438, also FC 87) appears within the apparent borders of M46. However, this nebula is most probably not a true member but is superimposed, or perhaps a passing "guest" ...
Source and more: SEDS
M46 - M47 - NGC2423 - NGC2425: A Quartet of Open Clusters.
March 20, 2009 18:44 - 19:14 UT.
Imaging: 135mm SLR Photolens, ATK16IC camera with Astronomik LRGB filters.
Exposures: Lum: 5x90s [1x1]; RGB 5x30s [2x2]; unguided.
April 1, 2007 19:35 - 19:45 UT and April 2, 2007 19:24 - 19:41 UT.
This object is very low for me - altitude 23 degrees - and I only have a very small window between houses and trees.
Imaging: William Optics Zenithstar 80 ED II APO, f/6.8 [focal length 545 mm] with 5 cm extender, Astronomik L-filter; ATK16IC b/w camera, K3CCDTools.
Exposures: Luminosity 10x20s + 9x40s + 1x90s; RGB 4x90s; autoguided.